Fumigant



Patented Nov. 14, 1944 UNITED STATES PATENT OFF-ICE i FUMIGANT Fred w. Fletcher and RobertR. Drelsbach, Mldland, Mich, assignors to The Dow Chemical Company, Midland, Mich, a corporation of Michigan No Drawing. Application June 1, 1942,

Serial No. 445,391

' 6 Claims. (Cl.1(i'739) The presentinvention relates to new and improved fumigants and fumigant mixtures and to a methodfor their use in controlling insect pests.

Many low boiling and volatile organic compounds have been suggested as fumigants, and carbon tetrachloride, methyl bromide, ethylene chloride, chloropicrin, and the like, are widely employed for the control of insect pests. These compounds vary considerably asto physical characteristics and a given toxicant may be limited in use to a particular type of fumigation procedure and the control of a specific insect.

Certain of the foregoing compounds in the amounts employed for fumigation are so lacking in odor as to necessitate mixing with lachrymators or'other warning agents. Others have injurious effects upon many of the products ordinarily contacted with fumigant materials, or corrode metals. Still other fumigants cannot safely be employed for treating seeds without materially lowering their germinating properties.

With increased inventories of surplus grains, the control of weevils and related insect pests by fumigation has become of major importance. Similarly, the increased demand placed upon established transportation systems requires efficient and rapid fumigation procedures in order that pests may be eliminated from box cars and the like so as not to infest uncontaminated materials which may be carried thereby. To accomplish these ends, a fumigant is desired which will be both rapid and thorough in its action and not be subject to the disadvantages set forth above.

It is among the objects of the present invention to provide a new fumigant and fumigant mixtures which have lachrymatory properties so as to preclude the necessity of adding otherwise inert and potentially corrosive warning agents thereto. A

further object is to provide such compositions which are more rapid in their action than are known fumigants. A further object is to supply fumigant compositions which will not have injurious effects upon wool, rubber, leather, feathers, fur, and the like, which will not be corrosive to metals, and which will not adversely affect the germination properties of seed which may be treated therewith. A still further object is to provide a method for the use. of such compositions. Other objects of the invention will become apparent upon consideration of the following specification.

The present invention provides new fumigants which comprise methyl isopropenyl ketone as a major toxic ingredient. These fumigants are faster in action and effective against a wider ketone with other known fumigants.

assortment of insect pests than are many known fumigants and fumigant mixtures. In the amounts required for the control of insect pests, methyl isopropenyl ketone is a strong and per sistent lachrymator, thus eliminating the necessity for incorporating warning agents therewith. The irritant property. of very dilute concentrations of methyl isopropenyl ketone is such that human beings and higher animals can withstand it for very short periods only. Furthermore, this action appears to be cumulative and does not decrease by reason of fatigue of the affected organs. At the concentrations required, methyl isopropenyl ketone has no apparent injurious effect on wool, rubber, leather, etc., and does not corrode metals. A further desirab1echaracteristic of this compound in-fumigation procedures lies in the fact that it hasno undesirable effect upon the germinating properties of seeds.

The invention contemplates the use in fumigation procedures of methyl isopropenyl ketone alone and also of mixtures of methyl isopropenyl In such combination, the methyl isopropenyl ketone serves both as a warning agent and supplementary toxicant and the effectiveness of the mixture is frequently much greater than might be predicted from a knowledge of the toxicity of the constituents thereof. A preferred embodiment of this phase of the invention resides in a mixture of methyl isopropenyl ketone with methyl bromide and is being described and claimed in a concurrently filed application Serial No. 445,392. Other representative combinations include mixtures of methyl isopropenyl ketone with such halo-nitroalkanes as chloropicrin and 1.1-dichloro-l-nitroethane.

In operating according to the present invention, from about 0.25 to 1 pound or more of methyl isopropenyl ketone may be employed per 1000 cubic feet of space to be fumigated, the preferred amount depending upon the organism to be controlled, th temperature, the exposure time, and the general construction of the fumigation enclosure. When employed with other known fumigants, the proportion of methyl isopropenyl ketone varies from a small fraction of 1 per cent, when used essentially as a warning agent, to from about .5 to per cent of the toxicant mixture where it is desired to take advantage of its parasiticidal action. Th preferred amounts of such mixtures employed fall within the range of from 0.25 to 1 pound per 1000 cubic feet dependent upon the particular insect concerned, the nature of the fumigation enclosure, the temperature, and the time of exposure.

The fumigants herein described are adapted to be employed in any of the accepted fumigation procedures. For example, they may be employed in household fumigation for the control of such common pests as cockroaches, mice, bedbugs, spiders, etc. They also may be employed for the fumigation of box cars and other common carriers to control mites, weevils, roaches, beetles, grain borers, mice, and the like. Other uses to which the new fumigants are adapted include tent fumigation of growing trees and plants, greenhouse fumigation, the bin fumigation of grain, seed fumigation, etc.

The compound methyl isopropenyl ketone embodies unsaturation of a type leading to the formation of semi-solid or solid polymerization products. While this tendency is not always encountered to an objectionable degree, it is sometimes desirable to incorporate into the liquid methyl isopropenyl ketone prior to vaporization in the fumigation operation a small proportion of a phenol and particularly of a polyhydroxy phenol such as hydroquinone, etc. The amount of such phenol employed is that required to serve as a stabilizer and is generally between about 0.001 and 0.1 per cent by weight. In the examples of the present application the methyl isopropenyl ketone employed was modified with 0.01 per cent by weight of hydroquinone in order that inconsistencies resulting from the presence of traces of polyme might be avoided.

The following examples illustrate the inven tion as regards th toxicity of the described compositions, their-mode of application, the particular insects controlled thereby, and the effect of the recommended treatment upon materials commonly subjected to fumigation. The invention is to be in no way limited thereby.

EXAMPLE 1 Methyl isopropenyl ketone was tested against a number of insect pests according to standard fumigation procedures at a constant temperature of approximately 25 C., and a relative humidity of 55 per cent 5 per cent. The followin results are representative:

aeeacvs Table 1! Concentration in 111,000 on. it.

Furnigant M. L. D.

6 hrs. exposure 100% mortality 5 hrs. exposure Chloropicriu Methyl isopropenyl ketone Methyl bromide Ethide"l.l-dichloro-l-nitroethane "Tritox' 'trlchloro-acetonitriie mica Less EXAMPLE 3 by weight of these two fumigants gave a kill of 95 per cent against the test insects in 5 hours exposure. At 0.2 pound per 1000 cubic feet, neither the methyl isopropenyl ketone nor the 1.1- dichloro-l-nitroethane killed any of the insects whatever.

EXAMPLE 4 In a similar determination, a per cent by weight mixture of methyl isopropenyl ketone and chloropicrin was employed at a concentration of 0.4 pound per 1000 cubic feet. This mixture gave a kill against Tribolium confusum of 93 per cent in 5 hours exposure. Chloropicrln at 0.2 pound per 1000 cubic feet gave no kill against the test insects.

EXAMPLE 5 To determine the effect of methyl isopropenyl ketone on materials commonly contacted with fumigants a number of organic products and metals were exposed to the compound in the amount of 1 pound per 1000 cubic feet over a period of 24 hours at 25 C. The following table sets forth the results obtained.

following table sets forth the results as obtained;

Table I Per cent mortality Insegt name Life stage 5 hrs. exposure 16 hrs. exposure 0 at f/Lmo 0.75 #11 000 0.3 #lLUOO 0,5 1!/l.000 cu. ft. cu.f cu. cu. ft.

Bedbug Adults and nymphs... I00 100 100 100 Rice weevil Adults l00 100 100 100 Pea weevil .d0 100 100 100 100 American cockroach Adults and nymphs... 96 100 so 100 German cockroach ..d0 100 100 100 m0 Large milkweed bug- 100 100 100 100 Milkweed bug 100 100 100 100 Cunaeus anguslum-.. 100 100 Med. flour moth. 100 100 100 100 Lesser grain borer 100 100 100 100 Confused flour beetle (Tribolium confusum) 100 100 100 100 EXAMPLE 2 Table III In comparative determinations, methyl .isopropenyl ketone .was compared with such {well 0 Materials fumigoted Observed result known and accepted fumigant materials as 0}110- ropicrin, methyl bromide, Ethide (1.1-dich1oro- Wool cloth No objectionable residual odor. l-nitroethane) and Tritox" (trichloroaceto- Rubber 3g; nitrile). The amount of each toxicant required ])Q to give a 50 per cent kill (expressed as median P- No ObJECUOIIBblE odor or ta te. lethal dose or M. L. D.) and the lowest concentta- No cnrrosion m ets, tion required to give 100 per cent mortality g against Tribolium confusum was determined under the conditions described in Example 1. The Do.

EXAMPLE 6 In a similarmanner seeds were fumigated with methyl isopropenyl ketone as described in Example 5 to determine the effect upon germination. The following table sets forth the results obtained in accordance with a standard germination procedure carried out upon both treated and untreated seeds.

Table IV Per Name or seed Treatment g nation I Clovcr Fumigated with methyl isopropenyl ketone, lit/1,000 cu. it. Do Check 81 Stringiess greenpod Fumigated with methyl isopropenyl 7i beans. ketone, l#/l,000 cu. ft.

o Check 68 Timothy Fumigated with methyl isopropenyl 95 ketone 1#/l,000 cu. it. Do C eck 96 Pioneer hybrid seed Fumigated with methyl isopropenyl 100 corn #307LF. ketoue, Iii/1,000 cu. it.

Do Check 97 While the foregoing examples describe the use volatile carriers to obtain compositions adapted to be sprayed or otherwise applied to materials infested with insect pests. In such compositions the active toxic principle is given up gradually over a period of time. Representative of the carriers which may be so employed are light petroleum distillates, white oils, ethylene chloride, carbon tetrachloride, propylene chloride, liquid halo-benzenes, hydrogenated naphthalene, etc.

We claim:

1. A method for controlling insects and related parasites comprising the step of exposing such organisms to the vapor of a. fumigant composition comprising monomeric methyl isopropenyl ketone as a major toxic ingredient.

2. A fumigant composition comprising a mixture of monomeric methyl isopropenyl ketone and chloropicrin.

3. A fumigant composition comprising a. mixture of monomeric methyl isopropenyl ketone and 1.l-dichloro-l-nitroethane.

4. A fumigant mixture comprising from 5 to 95 per cent by weight of monomeric methyl isopropenyl ketone in mixture with a halo-nitroalkane.

5. A fumigant mixture comprising monomeric methyl isopropenyl ketone and a halo-nitro-alkane.

6. A fumigant mixture comprising monomeric methyl isopropenyl ketone and a stabilizing amount of hydroquinone.

FRED W. FLETCHER. ROBERT R. DREISBACH. 

